HW5 20225421 Dahee Kwon

This homework is divided into 3 parts.
The first step is to convert light field images into 4D light field representation, and the second part is to refocus images at different depths. The last step is to compute an all-in-focus image and a depth map.
In this html file, I use the images that I captured by myself.
Detailed explanation about algorithm is described in the "AI621_HW5_20225421.html"

Refocusing and focal-stack generation

There are 5 images that focus at different point.

custom_stack = cell(5,1);
custom_stack{1} = imread('./custom/custom1.jpeg');
custom_stack{2} = imread('./custom/custom2.jpeg');
custom_stack{3} = imread('./custom/custom3.jpeg');
custom_stack{4} = imread('./custom/custom4.jpeg');
custom_stack{5} = imread('./custom/custom5.jpeg');

All-focus image and depth from defocus

I use various sigma1 and sigma2 then find the best one. (sigma1 = 1, sigma2 = 0.5)
Like the chesboard image, although the effect of sigma is not significant (at least within the range I choose), if sigma values are increased, the sharpness of focused image is lost and the depth map also seems more blurry.
Also, if the sigma1 is greater than 5, edge information appears to be more prominent than depth information.

sigma1 = 0.5;
sigma2 = 1;
 
fstack_lum = cell(5,1);
fstack_low = cell(5,1);
fstack_high = cell(5,1);
wsharp = cell(5,1);

%1
for i = 1:5
    tmp = rgb2xyz(custom_stack{i});
    fstack_lum{i} = tmp(:,:,2);
end
%2
for i  = 1:5
    tmp = im2double(imgaussfilt(fstack_lum{i},sigma1));
    fstack_low{i} = tmp;
end
%3
for i=1:5
    fstack_high{i} = fstack_lum{i} - fstack_low{i};
end
%4
for i = 1:5
    tmp = im2double(imgaussfilt((fstack_high{i}).^2,sigma2));
    wsharp{i} = tmp;
end

output
Since I couldn't take images in static position, the focusing performance is not perfect (compared to the chessboard example).
But it captured sufficiently sharp image compared to the original images.

nom = 0; denom = 0;

for i = 1:5

nom = nom + wsharp{i}.*im2double(custom_stack{i});

denom = denom + wsharp{i};

end

focused_img = nom./denom;

imshow(focused_img)

depthmap

nom = 0; denom = 0;

d_list = {0.2,0.4,0.6,0.8,1};

for i = 1:5

nom = nom + wsharp{i}.*abs(d_list{i});

denom = denom + wsharp{i};

end

depthmap = nom./denom;

imshow(depthmap)